Fluid turning blade



Oct. 14, 1952 D. J. CLARKE 2,513,911

FLUID TURNING-BLADE Filed Nov. 6. 1947 2 SI-lEETS-SHEET 1 Oct. 14, 1952 D. J. CLARKE FLUID TURNING BLADE 2 SHEETS-SHEET 2 Filed Nov. 6, 1947 Patented Oct. 14, 1952 FLUID TURNING BLADE Daniel Jarvis Clarke, Bay City, Mich., assignor to Stalker Development Company, Bay City, Mich., a corporation of Michigan Application November 6, 1947, Serial No. 784,457. 17 Claims. (01. 253-77) This invention relates toblades forturning or directing a. flow of fluid and particularly to blades for turbines or the like adapted to operate in a flow of hot motive fluid.

The principal object of the invention is to provide a fluid turning or directing blade structure adapted for operation in a turbine or other device where there is a hot gas flow, the blade being provided with a series of slots extending across its nose or leading edge from which a protective layer of cooling air or gas may be discharged to protect the entire nose surface of the blade against damaging contact with the hot gas flow.

F It is a further object to provide such a blade structure which is simple and inexpensive in construction, has adequate strength and reliabilty in operation, and which is provided with a pattern of slots across its entire nose or lead-- ing "edge from which a protective fiow of cooling fluid may be discharged.

It 'is also an object to provide a hollow blade formed by a pair of constituent parts stamped from flat sheet metal parts and fabricated into the shape of a hollow blade having the desired pattern of slots therein.

It is a further object to provide a hollow blade for a turbine or the like formed from a pair of stampings having complemental interfitting faces assembledv in overlapping relation to provide a series of spaced open slots extending acrossthe lnterfitted faces, the two ,stampings after being interfitted being formed into blade shape with the slots located across the nose or leading edge of the blade. f

It is also an object to provide a method of forming a hollow slotted blade for use in a turblue or the like in which a pair of constituent parts are stamped from a flat sheet of material, the two parts then being interfitted with each other and formed into the proper blade contour.

It is also an object to provide a method of forming a hollow blade having a pattern of slots over its leading edge or nose andwhich-is formed by stamping a pair of plates from flat sheet material having a series of notches along adjacent edges with the notches arranged in complemental relation, such plates being then interfitted or interlaced while fiat to form a series of open slots extending across the interfitted edges and the plates thereafter being bent to form the contour of a hollow blade with the slots located on the nose or leading edge thereof.

Other objects and advantages will be apparent from the following description, the accompanying drawings, and the appended claims.

In the drawings- Fig. 1 is a top plan view of the assembled blade of the present invention;

Figs. 2 and 3 are side elevational and perspective views thereof, respectively; Fig. 4 is a view in plan of the two complemental sheets from which the blade is fabricated following the stamping thereof and prior to being interfitted; I

Fig. 5 is a side elevational view of one of the stamped plates of Fig. 4; 1 n Fig. 6 is a plan view from the outside surface of the blade with the two plates assembled but prior to being formed to blade shape;v v

Fig. '7 is a View similar to Fig. 6 from the opposite side of the plates; Fig. 8 is a vertical sectional view on an enlarged scale through the nose of the blade looking toward the rear or thrust face an substantially on the line 8-8 of Fig. l; and Fig. 9 is a horizontal sectional view on an en larged scale through the nose of the blade on the line 99 which is shown in both Fig. 2 and Fig. I. n The fabrication ofv hollow blades for directing or turning a flow of fluid, such as forturbin'es and the like, presents considerable difliculty because of the severe conditions under which blades of this character are required to operate. They are subjected both to high centrifugal and other operating stresses and are also in many cases bathed by a hot gas fiow at temperatureswhich are so high that even stationary blades would be injuriously affected. To afford protection for such blades against this high temperaturecondition, a pattern of slots may be provided preferably extending across the nose of the blade in such relation that flows of cooling fluid may be discharged from the slots in such manner as to form a protective film thereover, such protective film preventing direct and impinging contact of the hot gas flow upon the blade surface in damaging relation thereto. Such slotted blade con--v simple in construction, being formedby punch;

ing, stamping, or a like operation from fiat sheet material. A pattern of notches defining a series of platelets therebetween is formed. along ad jacent edges of two such plates, the patternbeing similar on the two platesL-but staggered or offset from each other. Thereafter the formed edges are interlaced or interfitted, the platelets of the two sheets overlapping each other and thus forming a series of slots therebetween. Preferably the platelets are bent at a relatively small angle away from the plane of the remainder of the plate so that when interfitted the slots formed between overlapped surfaces of the platelets will be open, and so shaped as to direct the discharge fiow therefrom substantially tangentially across the nose surface of the blade, to thus afford protection for the entire exposed blade surface.

The platelets having been interlaced, are secured by welding projected portions or tabs thereon to the opposite plate, this being accomplished with the welded areas of both plates be- 1 ing located on the same side or surface of the plates, and in this way it is possible for all welded areas to be located on the inside of the formed blade where they will not be exposed, and thus not in position to impair or interrupt the smooth outer surface of the blade, nor to adversely affect its desired aerodynamic characteristics.

The two plates are formed into final hollow blade shape with -one plate constituting the camber side and the other the thrust side of the blade. The forming is so carried out that the pattern of slots is located on the nose of the blade, the length of the slots beingsuch that they extend across the nose and to some extent around to the opposite side faces of the blade, as far as'desired to'aiford the necessary protection. Suitable shims or spacers may be inserted in the slots during this part of the operation to maintain uniform slot widths.

When connected to a suitable source of fluid, such as an air compressor, the slots each discharge a flow which is projected substantially spanwise across the nose and forward portions of the side faces, forming a series of overlapping cooling and protective films which cover and thus protect the entire nose and forward surface of the blade. The flows also travel rear- Wardly over the remainder of the blade surface on both sides thereof, and thus afford proper protection for the blade surface against the hot gas flow. Protection for the entire nose surface is highly important and desirable as assuri'ng against damage to the blade notwithstanding movement or shift in the location of the stagnation point, i. e., the point where the flow divides, such shifting taking place with different operating conditions to which the blade is, subjected. In this way the entire nosearea which is the most exposed and difficult to protect, as well as the remainder of the blade surface, is adequately protected against damaging contactwith the fluidin which the blade is working.

Referring to the drawings which disclose a preferred embodiment of the invention, the blade is formed from two sheets of material such as fiat plates l0 and II, the plate H) being that adapted to form the camber side ofthe blade while the plate H is that forming the thrust side. These plates may be of suitable hightemperature and corrosion resistant alloy steel or other material having the necessary physical characteristics which will retain its strength at high temperatures while permitting the deformation required in the forming operations. A suitable sheet for example will be a sheet of gage stainless steel of high heat and corrosion resistant alloy, such as that sold by American 4 Rolling Mill Company as (ET-45 which has a high content of nickel and chromium.

A pattern of notches is provided in the adequate edges of each of sheets H3 and H, such notching being performed by convenient metal forming operations such as punching, stamping, or the like. Where the sheets are to be heat treated the stamping may be performed prior to the heat treatment, and the hardness and other characteristics desired may be developed following the completion of the stamping operations.

The notches in plate III are shown at I2 as of generally crescent shape, defining a series of platelets l4 therebetween. As shown, the notches are so formed that the platelets are defined by an upper curve l6 and lower curve It, these curves defining the outer or discharge end of the slot, and the inner or inlet end thereof, respectively. The inner corner of each platelet where it joins the main body of the plate is preferably notched out as shown at 20 to provide an additional recess for receiving the opposite platelet in the assembled form. Each platelet terminates in a tab 22, the tabs having such shape as to facilitate their being secured to the opposite plate surface.

Plate I I has a similar pattern of notches in its edge defining the series of platelets l5 bounded by the upper curve ll, lower curve l9, and having enlarged recesses 2| and tabs 23. The pattern however is staggered or offset from that of plate H) by a half lengthas shown i Fi 4.

In order to provide for forming open slots wit a slotted passage of predetermined width, the platelets of both series are preferably bent at a relatively small angle to the plane of the remainder of the plate, as shown in Fig. 5, the tabs however preferably remaining in the plane of the sheet to facilitate their joining with the opposite plate surface. This bending of the platelets may conveniently be accomplished at the same time and as part of the stamping or forming operation.

The two plates so formed are then interfitted or interlaced with each other into the arrangement shown in Figs. 6 and 7. It is found that this can readily be accomplished by holding the two plates slightly inclined relatively to each other, and by engaging the two series of platelets with each, other with a slight twisting motion the edges of the two plates can be readily brought together and the assembly made quickly and without difiiculty.

As shown in Fig. 6, the appearance, of the assembled plates from the side which is to con-. stitute the outside of the blade resembles a series of spade shaped members overlapping each other and being alternatively integral with the opposite plates, the platelets being bent slightly above the lane of the plates so as to define slots between each adjacent pair. It will further be noted that the length of each platelet is such in relation to the spacing of the platelets in the opposite series that there is a definite overlapping, indicated by the dotted lines in Fig. 6, thus defining the slotted passages 30 which have the curved and forwardly extending shape as indicated. I

On the rear side of the plates, 1. e., the side which is to constitute the interior of the hollow blade, the appearanceis as shown in Fig. 7. The tabs 22 are all in contact with a portion ofthe plate H spaced inwardly beyond the notches l3;

and similarly the tabs '23 are: allin contact .with

l the 'surface of-plate I0 inwardly beyond the notches l2. Thisfprovides for ready securing of the tabs to the'respective plate surfaces which is conveniently done by' brazing, welding; or other suitable-metal working step. It will be noted that this operation is performed without changingtheangular relationship of the platelets to the pla'ne'lof the sheet materialand thusthe slots 30 remain as open slots in the assembled conditior'rof the two plates. v

"Thereafter'theiassembled plates are bent into the form or contour of a blade, such as the shape indicated in'Figs. 1, 3 and 9 with plate l0 forming the camber side and plate .I l the thrustside of the blade. This is conveniently done by bending the plates about a form, the bending being so carried. out that the joinededges, and the slots 30 'willbe located upon the nose portion of the blade as indicated in Figs. 8 and9. Preferably these slots 30 are located substantially centrally of :;the nose and the series extends spanwise across the entire extent of the nose. By a suitable;selection of the shape ofthe notches and platelets, the slots can likewise be caused to extend-to. a greater or less extent around each side face of theblade, to thus discharge slot flows not only across the entire nose area but to some extent on the side faces as well. .--:As,-shown in Fig. 8 the slots30 have a predetermined width (distance between the overlapped portions of the platelets) as determined by the amount ofbending of the platelets, and the slots likewise have a definite axial length determined by the amount of overlapping between adjacent latelets. This length is desirable as providing a definite direction of discharge flow which is substantially tangentially across the face of the platelets, with the flow from each slot being substantially parallel to and in-overlapping elat on w e fl w r m. th oth r 5101534 n this ;way a highly L effective and substantially complete protective film is provided over the entire exposed nose area, and such flow is carried. around the sides of the blade to the'extent desired impartingadditional protection thereto.

In order to assure the maintenance'fofuniform thickness ofthe slots 30 during thefforrning or bending operation in which the twointerfitted plates are shaped to the' desired.bladecontour, suitable shims or spacers may v be insertediniea'ch of the slots 30 before this bending takes place..

theshims servingfito keep the s'lotsiopen and of uniform width; and being ffwithdrawn after, the bending and the shaping of'the blade is completed. It is also" possible in this way to control accurately the width of the slots by the selection of .shims of suitable gage or thickness. If desired the shims may be of tapering thickness so as to vary the shapeof each individual slot from one side or end thereof to the other, or if desired-the slots-maybe formed'to be of uniform width through their extent from one side of the blade to the other and from the inlet to the discharge 'end, thereof. This control Y through the use of ishims is advantageous as assuring the formation'of slots of uniform dimensions inthe final: blade. notwithstanding .minorvariations in the initial steps of punching and bending.

I 'Each' bladeis.suitably mounted'on a base- 32 and a tube 33 extends" through the base and establishes a flow passage for the cooling fluid which is supplied froma suitable source-such as a compressor and delivered to the interior of the hollow blade fordischarge from the slots.

' The invention thus provides a blade for. altur' him or; the like which is highly effective for the purpose desired, making it'ipossible to operate such blade under conditions-which would dth'ef-l wise be damaging to the material of thebla'de; The blade as constructed is simple. can be fabricated by relatively inexpensive metal forming processes-and the arrangement and pattern of the slots can be easily changed and predetermined as desired for different types. of blades. The blade in its finished'form is of strong and sturdy construction, thefabricating steps .described providing adequate strength for the blade at the-slotted area; 'andithus there is no tendency toward blade failure because of the slotting arrangement providedJfWith' this blade noperation, the entire nose surface is protected by a fluid flowsu'pplied fromv the interiorof the blade, and such protection remains effective notwith standing consider'able shift" in the stagnation pointidue to different operating conditions-.1:

While the method and form of apparatus. here in described constitutes preferred" embodiments of the invention it is to be understooduthat the 1 invention is not limited to this precise method and form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is: 1

1. A hollow blade for use in a turbine or the like comprising a pair of plates with notched interfitted edges having portions depressed at an angle tothe plane thereof defining a pattern of slots each extending at an acute angle to the face of said plates, the sheets being bent into blade shape'with the slots being located upon and extending across the nose of the blade and opening in a direction generally 'spanwise thereof.

' 2. A hollow blade for use in conjunction with a hot gas flow comprising a pair of sheet metal members with notchedv interfitting edges over-- lapping with each other and having portions thereof depressed at anangle to the plane of said members defining a series of slots with their openings spaced across the nose of the blade and with the length of said slots extending in a direction generally spanwise thereof. v

3.. A hollow blade for use in conjunction with a hot gas flow comprising a pair of sheet metal members having notched edges forming a'series of platelets having portions depressed at an angle to the plane thereof, the platelets of each of said members being interfitted and overlapped with the notches of the other said member forminga series of slots with their openings spaced across the nose of the blade and with their length extending'in a direction generally spanwise of the blade.

4. A hollow blade for use in a turbine or the like comprising a pair of sheet metal-members having notched edges forming a series of plate-, lets, the platelets of each said member being bent away from the plane of the sheet and being interfitted with the notches of the other member providing a series of overlapped slots the openings of which are spaced across the nose of the blade with said slots extending at a small angle to the nose of said blade and in a direction generally spanwise thereof.

5. A hollow blade comprising a pair of sheet metal plates stamped with a series of elongated complemental notches therein defining a series of staggered platelets on adjacent edges with portions thereof deflected at an angle to theplane 7, I thereon-said plates'having their adjacent .aedges interfitted' and secured together leaving atserisi of slots therebetweent'definedby the -wallsof said platelets, said platelets said interfitted relationfoverlappingpeach: other defining a series of slots with :theirax'es atan angle to the 'fa'ceV-of said plates adapted to discharge .a flow t'suo'e stantiallytangentially across the blade surface, said plates "being benti-nto blade shape with: said slots-located. on andiextending across'the nose of said blade. 11"." r

- '6. A hollow bladescomprising'twdplatesfeach having .:a plurality of" notches .therei'n defining a series :zOf platelets therebetween. with portions thereof. at an-angle to :the' plane of said plates. said zplates beingssecuried- 'in. 'interfitting relation with each other with the platelets of each plate occupying a notch of the. other plate, the platelets of-tine said plate overlapping the platelets of the othersaid plate forming a series ofslots having I their axes at an angle to the face of said plates and opening in a direction genera-11y spanwise'oi the blade, and said plates-"being curvedto :define the oppositexsurfaces of a hollow blade:

a l; nxhollow blade comprising two platesieach having a plurality of notches therein defining :a series of platelets therehetween, said plates being secured-in inte'rfitting relation with each other with the platelets of each plate occupying a notch of the other plate, the plateletsuofoneisaid plateoverlapping the platelets-of the'rother said plate forming a series of slots therebetween, said platelets being'bent rat a small angle tothe plane of said plates to provide for opening the slcts between, adjacentplatelets, and said platesbeing curved to define the surfaces of hol-l ow bladie. .-8, ,A hollow "blade 'of the character described comprising two plates each having-ap1uralitypf notches therein 'defininga series of platelets therebetween, said plates being secured in interfitting relation to each other :with the platelets of each plate 'occIupyhdgEanotch oi the "other-said plate :and being spaced apart itozform Ta series {6f discharge s'lots between-them to" direct news of the putter ems substantially tang entially alon sur'face'of thefblafde. i I 7 holl ow'blade of he "c'ha-ra ter described c m i a P f'i l tesi pl r ity'ofnotchesjinthe edgethere efin nrg a series of. platelets therebetween, said I p ates "b eing' welded together with the platelets hit one said plate ovenaisiing the platelets .oi the, .othersaid plate and received within the notches 'theiother said zplate,lthe edges .ofboth saidlplateswl yi'ng within the interior ef-said blade. a a ;-l-.0.;A -ho1lo.w' blade'of the ehamcterdeseri ae l comprising a {patr ot pla-tes reach haying a phi-1 rality of notches in the edge thereof definine a'a' series of platelets. therebetween', '.Sfil&'"llfil70h6$ having enlargements 'atthei cornerstefisai'd'plat lets, said plates beinig weldeditcgethe *withi'tn-e platelets 'or oz-iesain iateevenappi g the' -platelet s of the other saia p1 teandpeing v within the "notches'o'f th'e-pth'ec saiii' pl eitending into saidenlargement, "the edgesf'd f both saidpleit's flying withinf'thefinteri'oit of said blade and being securedrespectivelytothe' oppo site said plate to retainthe'plate s relation. 7 to .i V

' '11. The method qr fabricating; afhdlloiv'blade adapted for usein eoiiiunction ii itk'a QhoMgJS iioiv' which comprises stamp nga Qp'airo sheet m was a ge' a a ra es as;

semble'ld l notches therein .bncxadi'acerit faces, interfittins said stamped plates: with each, other to fnrm'ca series f op n slots and s curin sa not hed edges-of oneplate tothe icomplemental portions of the other said plate, and bending" theplates to constitute opposite faces of "a hollow blade with said series of .slotswbe'ing located on-and extend: ing across the nose of the blade-and opening-in a direction generallyspanwise of saidblade.

- "12. The method of fabricating a hollow blade for use in a turbine or the like which comprises stamping a pair of fiat sheetmetal p'lates'haiiing complemental platelets and notches :therei-n on adjacent faces, interfitting said stampediplatelets with each other 'toitorrn. a series of zslotstwith overlapping edges se'curingisaid interfitte'd platelets toea'ch othen and bending the plates toxconr-v stitute opposite faceslot' a hollow bladewith'said series of slots being located on and extending across the nose of the blade rand-opening in la direction generally s panwise thereofl" I 1-3; The method of fabricating a hollowcsblade for use a turbin-e' orthe like which comprises stamping pair of flat sheet metal plates having complementa'l platelets and notches therein? :on adjacent faces, bending said formed platelets away from the plane-of said -plates, i=nterfitting said stamped platelets with each other to for-m a series of slots with" overlapping edgesand securing said 'platelets' in said interfitted relation, said'be'nding of [said platelets iorming' slot-"open ings directed substantially tangentially across I the surface; and bendingthe plates to constitute opposite faces of a hellow blade with' said series of slots being located on and'extendirig acrossthe nose of the blade-andop'ening in adirectionigenerally spanwise of the blade; I '14. The method-offfabricating afluid-turning blade comprising thesteps of stamping notches along the free edge portions of two platesto i'o'rm thereon a pluralityof spacedplatelets interlacing said platelets in overlapping relation forming a series of slots "with overlapping edges-welding the edges of said platelets to the adjacentsur face of the other said plate leaving-said slots open, and jforrhingtheplatesinto a'form eta-hol- 1-5. ,Th'e rnethod of fabricating a fiuidturning blade comprising 'thei steps ofsta'mping notches along thefre'e' edge portions of two platestoform thereon afplurality of spaced platelets, interlacing said platelets both platesfin overla pin r if n fanning ais ri' s; tropes slots therebe tw n,Se urin ;saidginterlacedip lates permanent- -1l7. The metho 10 REFERENCES CITED The following references are of record in the file of this patent:

Number UNITED STATES PATENTS Name Date Wilmot Oct. 29, 186-7 Shepherd Feb. 6, 1912 Meyer Nov. 5, 1940 Clarke Nov. 29, 1949 

